Method of and apparatus for coating articles



E PUGH April 26, 1932.

METHOD OF AND APPARATUS FOR COATING ARTICLES Filed Dec. 51 1928 2 Sheets-Sheet /m em0/ I [mama/7 Pug/7 My April 26, 1932. E. PUGH 1,855,869

METHOD OF AND APPARATUS FOR COATING ARTICLES Filed Dec. 31, 1928 2 Sheets-Sheet 2 Wye/7f 5/76/60 Pay/7 Patented Apr. 26, 1932 PATENT OFFICE OH PUGH, OI DOWNEBS GROVE,

001mm, mcoarona'rnn, or new You,

ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC N. Y A CORPORATION 01 NEW YORK METHOD AND APPARATUS FOR COATING ARTICLES Application filed December 81, 1928. Serial No. 829,588.

This invention relates to methods of and apparatus for coating articles, and more particularly to methods of and apparatus for finishing metal parts.

The principal objects of the invention are to provide a simple and ex editions method of and apparatus for a plylng material uniformly to exposed sur aces 0 articles.

In order to accomplish these objects in accordance with the invention, one embodiment thereof contemplates the conveying of metal parts or other articles to be coated through a closed chamber, the parts on the conveyor being connected in their passage therethrough to one terminal of a score of electrical energy of high potential. The opposite terminal of this source is connected to a nozzle throu h which an atomized spray of coating material is introduced into the chamber, thus giving the particles of the coating material suspended in the atmosphere of the chamber a charge 0 posite to that of the metal parts. These particles are thus selectively attracted to the uncoated portions of the parts in preference to the portions already covered by the solvent of the japan or other coating material so that they are deposited upon the uncoated surfaces thereof. To prevent the undue deposition of particles of coating material upon the interior of the chamber, the

chamber wall is connected to the source of electrical energy so that it has the same potential as the nozzle.

It is believed that a complete understanding of the invention may be had from the following detailed description, taken in conjunction with the aocompanying drawings, in which Fig. 1 is a fragmentary plan view of an apparatus embodying features of the invention and which may be employed in practicing the method;

Fig. 2 is a front elevational view thereof with the front wall of the chamber removed;

Fig. 3 is an enlarged sectional view taken on line 3-3 of Fig. 2, showing the electrical equipment associated with the apparatus, and

Fig. 4 is an enlarfged perspective view of one of the supports or carrying the parts to be coated.

Referring now to the drawings wherein the same reference numerals indicate similar parts throughoutthe various views, the numeral designates a chamber made of sheet metal having four pairs of swinging doors 11-11 which are so mounted as to always return to a closed osition. This arrangement divides the charm or into three compartments 12, 13 and 14 so that compartments 12 and 14 serve as air locks for the middle compartment 13. Partitions 22-22 (Fig. 3) are provided under each pair of swinging doors 11-11 to prevent the circulation of air between the compartments. At both ends of the chamber 10 are sprockets 1515 and 16-16 suitably mounted on shafts 17 and 18, respectively, and adapted to enga operatively and support an endless s roc et chain 20 in its passage through the c amber. Secured to the chain at equal spaces throughout its length are supports for carrying parts 26 to be coated.

Each of the supports 25 includes an insulator 27 ri 'dly held in an upright position by a pair 0 angular members 28-28 secured to the sides of the chain 20. A metal cap 29 secured to the lower end of the insulator 27 is connected to a metal rod 30 mounted in the center of the insulator and terminating near the upper end thereof in a pair of laterally extending arms 31-431 which are provided with hook portions 32-32 for supporting the parts 26 to be coated. At the upper end of the insulator 27 is a substantially rectangular guard 35 rigidly fastened thereto by a pin 36. This guard extends out beyond and surrounds the hook portions 3232 so as to engage the swingin doors 11-11 and thus prevent injury to t e parts 26 in their passage through the chamber.

A current conducting rail for making contact with the metal caps 29 of the supports 25, is insulatively mounted on the bottom of the chamber 10 by means of insulating blocks 41-41 and is connected tothe negative terminal 43 of a source of um-direct ona1 electrical energy roduced by a mechanical rectifier 44 (Fig. 3 from a source of alternating current (not shown). The positive terminal 42 of the rectifier 44 is connected to the walls of the chamber 10 and also to a plurality of atomizing devices 45 su1tably mounted alongside t e chamber, as illustrated in Figs. 1 and 3.

Each of the atomizing devices 45 comprises a nozzle connected to a source of compressed air (not shown) and having its forward end attached to the u per end of a tube 51, the lower end of the tu e being immersed in a liquified coating material 52, such as japan, lacquer, paint, etc., within a container 53. From the foregoing description it Wlll be readily understood that upon compressed air being admitted to the nozzle 50, the emission of the air past the upper end of the tube 51 creates a vacuum therein whereby the liquefied coating material 52 is drawn up in the tube and the force of the air breaks the coating material into finel divided particles and blows it into the middle compartment 13 through apertures 55 in a wall of the chamber 10.

In practicing the invention, the shaft 17 is connected to and driven b any suitable source of power (not shown so as to rotate the sprockets 1515 keyed thereto and efl'ect the movement of the sprocket chain 20 in the direction indicated by the arrows in Figs. 1 and 2. With the negative terminal 43 of the mechanical rectifier 44 connected to the current conducting rail 40 by a conductor 59, and the positive terminal 42 connected to the chamber 10 and the nozzle 50 by a conductor 60, the mechanical rectifier is operated to create a uni-directional current of high potential. The parts 26 to be coated are then placed on the hook portions 3232 of the metal rods 30, and as the guards 35 en age and open the doors 11-11 in passing rom compartment 12 into compartment 13 of the chamber 10, the metal caps 29 make contact with the current conducting rail 40. This contact connects the parts 26 to the negative terminal of the source of uni-directional electrical energy through laterally extending arms 31-31, metal rod and cap 30, 29, respectively, contact rail 40, and conductor 59 to the negative terminal 43 of the mechanical rectifier 44. As has been previously explained, the nozzle 50 of the atomizing device 45 is connected to a source of compressed air to effect the introduction of a coating material 52 in finely divided particles into the compartment 13. Since the atomizing device is connected to the positive terminal of the source of uni-directional electrical ener through nozzle 50, conductor 60 to the positive terminal 42 of the mechanical rectifier 44, the particles of coating material are given a positive charge as they emerge from the atomizing device 45 into the com artment 13 through apertures 55 in the cham r 10. The negatively charged parts 26 to be coated attract the positively charged particles of coating material so that the latter is deposited upon the surface of the parts 26 to form coatings thereon. A uniform coating of each art is assured, due to the fact that as the particles of the coating material are deposited thereon, the solvent of the coating material acts as a dielectric, whereby the positive charge is intensified at the uncoated spots on the parts 26 to better attract the particles of coating material thereto.

The difference of electrical potential between the parts 26 to be coated and the atomizing devices 45 can be varied greatly, depending on size of the chamber, the characteristics of the particular coating material used and the speed im arted to the conveying chain 20, but the v0 tage should not be of such a value as to cause arcs between the parts being coated and the atomizing devices or chamber walls. The connecting of the walls of the chamber 10 and the atomiging devices 45 to the same terminal of the source of unidirectional electrical energy produces positive charges on both the coating material 52 and the walls of the chamber 10 so that the particles of coating material are repelled from. the walls to prevent undue deposition thereon. In order to ca ofi any excess coating material, the bottom of the chamber 10 is sloped toward a drain 64 (Fig. 3).

As the finished parts emer from the chamber 10, they are removed rom the supports 25 and uncoated parts are placed on the hook portions 32-32 and they in turn are carried through the chamber 10 so that the process is a continuous one.

It will be understood that the embodiment of the invention herein described and illustrated is merely a convenient and useful form of the invention which is ca able of many other modifications without diaparting from the spirit and scope of the invention.

What is claimed is:

1. A method of applying a finish to an article of manufacture, consisting in finely dividing a coating material, surrounding the article of manufacture to be coated with an atmosphere having the finely divided material suspended therein, and subjecting the article of manufacture and the particles of the material to a difference of electrical potential to cause the material to be attracted to and deposited upon the article of manufacture.

2. A method of applying a finish to an article of manufacture, consisting in producing a uni-directional current of high voltage in an its accuses atmosphere, introducing a coating material in a finely divided form mto the atmosphere, and subjecting the article of manufacture to be coated to the current and the atmosphere for a predetermined period of time to cause electrical deposition of the material upon the article of manufacture.

3. A method of applying a finish to an article of manufacture, consisting in enclosing an article of manufacture to be coated, connecting a. the article of manufacture to be coated to opposite terminals of a source of uni-directional current of high voltage, introducing an atomized coatin material into the enclosed atmosphere, an subjecting the enclosure to the same potential as the coating material to reel the rticles of coating material thererom as t ey are attracted and deposited upon the article of manufacture.

4. In an apparatus for applying a finish to an article of manufacture, a chamber for enclosing the article of manufacture to be coated, an air lock therefor, means for introducing into the chamber coating material in finely divided form, means for conveying the article of manufacture through the air lock into the chamber, means for connecting the article of manufacture for a predetermined period of time to one terminal of a source of uni-directional energy, and means for connecting the coating material to the opposite terminal of the source of electrical energy to cause the deposition of the coating material upon the article of manufacture.

5. In an a paratus for applying a finish to an article of manufacture, a closed chamber for receiving an article of manufacture to be coated, an atomizing device for introducing a spray of coating material into the chamber and a source of electrical energy associated with the chamber for subjecting the article of manufacture to one potential and the atomizing device and the chamber to an opposite otential to cause the deposition of the coatmg material upon the article of manufacture and prevent the deposition thereof upon the chamber wall.

6. In an apparatus for applying a finish to an article of manufacture, a chamber for enclosing the articles of manufacture to be coated, means for conveying the articles of manufacture therethrough at predetermined intervals, means for connecting the articles of manufacture to one terminal of a source of electrical energy at a predetermined time, an atomizing device for injecting particles of a coating material into the chamber, and means for connecting the atomizing device and the walls of the chamber to the opposite terminal of the source of electrical energy to repel the particles of coating material from the walls as they are attracted to and deposited upon the articles of manufacture.

7. A method of applying a finish to an artisupply of coating material and t cle of manufacture consisting in enclosing a space of predetermined size, introducing into t e enclosed atmosphere a coating material in a finely divided form, conve 'ng the articles of manufacture to be ooa through the enclosed atmosphere in s aced relation, and subjecting the articles 0 manufacture and the coating material to a difierence of electrical potential to cause the coating material to be deposited on the articles of manufacure.

8. A method of supplying a finish to an article of manufacture consisting in enclosing an article of manufacture to be coated, connecting a supply of coating material and the article of manufacture to be coated to opposite terminals of a source of uni-directional current of high voltage, introducing an atomized coating material into the enclosed atmosphere, subjecting the enclosure to the same potential as the coating material torepel the particles of coating material therefrom as they are attracted and de osited upon the articles of manufacture, and imparting movement to the article of manufacture relative to the enclosure.

9. In an apparatus for appl ing a finish to an article of manufacture, a c amber for enclosing the articles of manufacture to be cost ed, a conveyor for moving the articles of manufacture therethrough at predetermined intervals means carried by the conveyor for electrically connecting the articles of manufacture to one terminal of a source of electrical energy at a predetermined time, an

atomizing device for injecting particles of a coating material into the chamber, and means for connecting the atomizing device and the walls of the chamber to the opposite terminal of the source of electrical energy to repel the particles of coating material from the walls as they are attracted to and deposited upon the articles of manufacture.

10. In an apparatus for applyin a finish to an article of manufacture, a cham r for enclosing the articles of manufacture to be coated, a conveyor for moving the articles of manufacture therethrough at predetermined intervals, means carried by the conveyor for carrying the articles of manufacture, means for cooperating with said carrying means for electrically connecting the articles of manufacture to one terminal of a source of electrical energy at a predetermined time, an atomizing device for injecting particles of the coating material into the chamber, and means for connecting the atomizing device and the walls of the chamber to the opposite terminal of the source of electrical energy to repel the particles of coating material from the walls as they are attracted to and deposited upon the articles of manufacture.

11. A method of applying a finish to an article of manufacture, consisting in enclosing a space of predetermined size, introduc- III 4 nausea ing into the enclosed atmosghere a coating material in a finely divided orm, conveyin the article of manufacture to be coate through the enclosed atmos here, and sub jecting the article of menu acture and the coatin material to a difference of electrical potential to cause the coating material to be de osited on the article of manufacture.

n witness whereof, I hereunto subscribe w my name this 19th day of December, A. D.

EMERSON PUGH.

D I 80 LA! M E R 1,855,869.Emera0n Pugh, Downers Grove, Ill. Mn'mon or AND Arrana'rus non COATING An'rionne.

pony, Ina, assenting and concurring.

Hereb enters this disclaimer to claims 2 an Gazette December 8, 1936.]

Patent dated A 26, November 10, 1936, by the patentee; t

1932. Disclaimer filed e aselgnee, Western Com- (1 11 in said specification.

4 nausea ing into the enclosed atmosghere a coating material in a finely divided orm, conveyin the article of manufacture to be coate through the enclosed atmos here, and sub jecting the article of menu acture and the coatin material to a difference of electrical potential to cause the coating material to be de osited on the article of manufacture.

n witness whereof, I hereunto subscribe w my name this 19th day of December, A. D.

EMERSON PUGH.

D I 80 LA! M E R 1,855,869.Emera0n Pugh, Downers Grove, Ill. Mn'mon or AND Arrana'rus non COATING An'rionne.

pony, Ina, assenting and concurring.

Hereb enters this disclaimer to claims 2 an Gazette December 8, 1936.]

Patent dated A 26, November 10, 1936, by the patentee; t

1932. Disclaimer filed e aselgnee, Western Com- (1 11 in said specification. 

